Five-aza-2'-deoxycytidine-induced hypomethylation of cholesterol 25-hydroxylase gene is responsible for cell death of myelodysplasia/leukemia cells.
Five-aza-2'-deoxycytidine-induced hypomethylation of cholesterol 25-hydroxylase gene is responsible for cell death of myelodysplasia/leukemia cells.
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DOI：
10.1038/srep16709
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发表时间：
2015-11-18
影响因子：
4.6
通讯作者：
Tohyama K
中科院分区：
文献类型：
--
作者：
Tsujioka T;Yokoi A;Itano Y;Takahashi K;Ouchida M;Okamoto S;Kondo T;Suemori S;Tohyama Y;Tohyama K
DNA甲基转移酶抑制剂（DNMT抑制剂）用于高危MDS，但其作用机制尚未完全了解。因此，我们进行了全基因组DNA甲基化测定，并集中在胆固醇25-羟化酶（CH 25 H）的基因，其表达上调，其启动子区域低甲基化后，地西他滨（DAC）在体外治疗。CH 25 H催化胆固醇的羟基化并产生25-羟基胆固醇（25-OHC）。虽然CH 25 H mRNA表达水平最初在MDS/白血病细胞系中较低，但暴露于DNMT抑制剂增强了CH 25 H mRNA表达。HL-60和MDS-L细胞中CH 25 H的启动子区最初是高甲基化的，但DAC处理诱导它们的低甲基化以及CH 25 H mRNA表达增加、CH 25 H-氧固醇途径激活、25-OHC产生和凋亡细胞死亡。我们进一步证实，正常的CD 34阳性细胞显示低甲基化状态的CH 25 H基因的启动子区。通过将shRNA慢病毒载体转染到细胞系中的CH 25 H敲低部分地保护细胞免于DAC诱导的细胞死亡。外源性添加25-OHC抑制白血病细胞生长。本研究提出了DNMT抑制剂通过其低甲基化机制激活CH 25 H-氧固醇通路并诱导白血病细胞死亡的可能性。CH 25 H基因启动子分析及DNMT抑制剂对MDS/白血病的治疗作用有待进一步研究。
DNA methyltransferase inhibitors (DNMT inhibitors) are administered for high-risk MDS, but their action mechanisms are not fully understood. Hence, we performed a genome-wide DNA methylation assay and focused on cholesterol 25-hydroxylase (CH25H) among the genes whose expression was up-regulated and whose promoter region was hypomethylated after decitabine (DAC) treatment in vitro. CH25H catalyzes hydroxylation of cholesterol and produces 25-hydroxycholesterol (25-OHC). Although CH25H mRNA expression level was originally low in MDS/leukemia cell lines, exposure to DNMT inhibitors enhanced CH25H mRNA expression. The promoter region of CH25H was originally hypermethylated in HL-60 and MDS-L cells, but DAC treatment induced their hypomethylation together with increased CH25H mRNA expression, activation of CH25H-oxysterol pathway, 25-OHC production and apoptotic cell death. We further confirmed that normal CD34-positive cells revealed hypomethylated status of the promoter region of CH25H gene. CH25H-knockdown by transfection of shRNA lentiviral vector into the cell lines partially protected the cells from DAC-induced cell death. Exogenous addition of 25-OHC suppressed leukemic cell growth. The present study raises a possibility that DNMT inhibitors activate CH25H-oxysterol pathway by their hypomethylating mechanism and induce leukemic cell death. Further investigations of the promoter analysis of CH25H gene and therapeutic effects of DNMT inhibitors on MDS/leukemia will be warranted.